The Great Purge was a series of campaigns of political repression and murder in the Soviet Union orchestrated by Joseph Stalin from 1937 to 1938. It involved a large-scale purge of the Communist Party and government officials, repression of peasants, Red Army leadership, and the persecution of unaffiliated persons, characterized by widespread police surveillance, widespread suspicion of "saboteurs", imprisonment, and arbitrary executions. In Russian historiography the period of the most intense purge, 1937–1938, is called Yezhovshchina (Russian: ежовщина; literally, the Yezhov regime), after Nikolai Yezhov, the head of the Soviet secret police, NKVD.

In the Western world, Robert Conquest's 1968 book The Great Terror popularized that phrase. Conquest's title was in turn inspired by the period of terror (French: la Terreur) during the French Revolution.

The term "repression" was officially used to denote the prosecution of people considered as counter-revolutionaries and enemies of the people. The purge was motivated by the desire on the part of the leadership to remove dissenters from the Party and what is often considered to have been a desire to consolidate the authority of Joseph Stalin. Additional campaigns of repression were carried out against national minorities and social groups which were accused of acting against the Soviet state and the politics of the Communist Party.

The term show trial is a pejorative description of a type of highly public trial in which there is a strong connotation that the judicial authorities have already determined the guilt of the defendant. The actual trial has as its only goal to present the accusation and the verdict to the public as an impressive example and as a warning. Show trials tend to be retributive rather than correctional justice. The term was first recorded in the 1930s.

Cadaver Trial was a posthumous trial over Catholic Pope Formosus held in 897.

In the late 17th century, various people in Salem, Massachusetts were accused of practicing witchcraft and consorting with the Devil in the Salem witch trials. Nineteen people were executed, one was killed, and five died in prison.

The Dreyfus affair was a show trial in France in 1894, where a Jewish captain, Alfred Dreyfus, was accused of spying for Germany.

The trial of Sacco and Vanzetti in 1927 was one in which two anarchist Italian immigrants were accused of an armed robbery in Massachusetts. Both were executed, despite international appeals.